1. Field of the Invention
This invention relates to edge sealing agents employed in the fabrication of containers or pods containing photographic processing fluid for in-camera developing, and in particular to pods having improved polymeric edge sealing agents that are insoluble in aromatic alcohols.
2. Prior Art
Homopolymers and copolymers suitable for forming the relatively weak burst seal in a pod have been known. Such seal materials are generally located along that edge of a pod which is intended to burst for releasing the photographic developer, and are coated over an inner layer of the pod which is poly(vinyl chloride) or other polymer that resists the developer.
Reference is made to the following representative patents and a publication describing the named seal compositions and others:
3,056,491 -- PLASTICIZED AND UNPLASTICIZED POLY(VINYL BUTYRAL); ALSO A COMPOSITION COMPRISING POLY (VINYLIDENE CHLORIDE),POLYACRYLONITRILE -- POLY(VINYL CHLORIDE, AND AN ACRYLIC ESTER RESIN.
3,056,492 -- CELLULOSE NITRATE - ACRYLIC ESTER RESIN COMPOSITION.
3,438,550 -- VINYLIDENE CHLORIDE - NITROCELLULOSE, ETHYL CELLULOSE -- ACRYLIC ESTER RESIN.
3,750,907 -- A MIXTURE OF CELLULOSE NITRATE OR ALCOHOL SOLUBLE CELLULOSE ACETATE BUTYRATE WITH STYRENEMETHYL METHACRYLATE COPOLYMER OR TOLUENE SOLUBLE CELLULOSE ACETATE BUTYRATE OR POLY(VINYL BUTYRAL),
A MIXTURE, WITH A PLASTICIZER, OF ALCOHOL SOLUBLE CELLULOSE ACETATE BUTYRATE, OR A COPOLYMER OF BISPHENOL A with epichlorohydrin, or toluene soluble cellulose acetate butyrate.